Junction boxes are enclosures that protect electrical connections, for example, from foreign matter and contaminants that could dislodge or jeopardize the connection. In case of a fire, the junction box acts as a fire enclosure that serves to contain the fire.
Junction boxes are required by building and electrical codes in many jurisdictions and, in their basic form, are familiar and age-old electrical components. Often viewed as a commodity component, most junction boxes are little more than metal or plastic boxes with holes—or knock-outs for holes. While traditional junction boxes work quite well for high-voltage connections, technology has changed, and many construction projects now use low-voltage power in addition to high-voltage.
The definition of low voltage varies depending on the source one consults, but for purposes of this description, voltages under about 50V may be considered low voltage. Low voltage power may be used for solid-state lighting (i.e., lighting based on light-emitting diodes (LEDs)), it may be used for control and automation, or it may be used for other kinds of household and commercial building systems.
Most low-voltage components require a separate driver to be installed. In broad terms, a driver is a transformer-rectifier that converts high-voltage alternating current (AC) power to low-voltage direct current (DC) power. For example, a driver may convert from 110 or 277 VAC to 12 V or 24 VDC. A typical driver has a set of high-voltage inputs and a set of low-voltage outputs. The inputs and outputs are usually in the form of wires, although terminal blocks and other structures may be used.
Regulations in at least some jurisdictions require that a driver be enclosed, and that high-voltage connections be separated from low-voltage connections. Thus, a number of manufacturers have created junction boxes that have space and mounting structures for a driver, as well as compartments to separate high- and low-voltage connections.
U.S. Pat. No. 9,951,934, which is incorporated by reference in its entirety, is the work of the present assignee and describes junction boxes that are suitable for use with a wide variety of different drivers. These junction boxes feature an open central area and two identical compartments, one on each end of the central area. The central area provides ample space and mounting structures for securing drivers, and the two compartments provide separate spaces for making high- and low-voltage connections. The presence of two identical compartments gives the junction box symmetry, so that either compartment can serve as the high-voltage compartment and either can serve as the low-voltage compartment. The junction boxes disclosed in U.S. Pat. No. 9,951,934 have a number of advantages, including ease of access and ease of driver installation.
Over the last few years, drivers have gotten considerably smaller as some manufacturers have perfected techniques for miniaturizing the necessary components. Unfortunately, junction box technology has not advanced at the same rate, and most available junction boxes are much larger than the smallest drivers. Yet making a junction box smaller is not a trivial exercise—for example, regulatory requirements may specify that the compartments for making electrical connections must have at least a certain minimum volume.